1. Field of the Invention
This invention relates to new and useful improvements in apparatus for pulling electrical cable through conduits in buildings.
2. Brief Description of the Prior Art
In the construction of residential, commercial, and/or industrial buildings, it is necessary to provide electrical service at many locations. This is accomplished by pulling electrical cable through conduits which may be in a variety of locations, e.g. underground, overhead, eye level, enclosed, etc. A common procedure is to provide a pull line or rope through each electrical conduit which is attached at one end to the electrical cable and at the other end to a powered pulley or the like to pull the cable through the conduit.
The design and layout of the electrical conduits is dictated by standard electrical design codes, ordinances, and the like. One design factor which is considered in conduit design is angular bends in the conduit. For any given electrical cable, there exists a maximum angle or minimum curvature radius that the cable can be bent in order to avoid permanent damage to the cable. Apparatus which has previously been available has been lacking in portability and in flexibility of operation.
One such apparatus, which is commercially available is the Greenlee "Porta Puller" for pulling cable. This equipment is quite bulky and difficult to carry which reduces its portability. Also, it had the disadvantage that it cannot pull cable around sharp bends, as where it is necessary to pull a cable upward, around a pulley and back down.
Gebo U.S. Pat. No. 4,337,924 discloses a powered cable pulling apparatus having extensible arms which support pulleys over which the cable is pulled. This apparatus has no provision for protecting the cable against damage when pulling through a 180.degree. bend.
Newell U.S. Pat. No. 3,968,952 discloses a cable pulling apparatus which is portable and has a powered winch which pulls the cable over an adjustably positioned set of pulleys. This apparatus is inflexible in the number of different locations in which it can work and does not protect the cable when pulling through sharp bends.
Oleson U.S. Pat. No. 3,190,616 discloses another type of cable pulling apparatus which is portable, but which is quite limited in the number of different positions in which it can work.
Jones U.S. Pat. No. 3,072,382 shows a powered winch arrangement for pulling electrical cable. This apparatus is flexible in operation but does not have adequate portability or protection of the cable in pulling through sharp bends.
Gebo U.S. patent shows a system of pulleys for pulling electrical cable. This is not a portable, self contained apparatus.
Elliott U.S. patent shows a truck mounted power winch for general purpose load handling and cable pulling.